Skip to content
Fencer Intel
critical 9.8

CVE-2011-10018 json

myBB 1.6.4 Backdoor Arbitrary Command Execution

published 2025-08-13 14 mo ago modified 2026-06-16 4 mo ago also EUVD-2011-5246

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
1
Metasploit

Summary

myBB version 1.6.4 was distributed with an unauthorized backdoor embedded in the source code. The backdoor allowed remote attackers to execute arbitrary PHP code by injecting payloads into a specially crafted collapsed cookie. This vulnerability was introduced during packaging and was not part of the intended application logic. Exploitation requires no authentication and results in full compromise of the web server under the context of the web application.

Patch / fix

Timeline

  1. First public exploit (Metasploit exploit/unix/webapp/mybb_backdoor)
  2. Published

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
14 mo ago

Exploit prediction

3.02% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Metasploit exploit/unix/webapp/mybb_backdoor myBB 1.6.4 Backdoor Arbitrary Command Execution metasploit exploit, excellent rank, 2011-10-06
  • raw.githubusercontent.com https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/unix/webapp/mybb_backdoor.rb referenced PoC, tagged "exploit" by a source, unverified
  • exploit-db.com https://www.exploit-db.com/exploits/17949 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 10.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CNA 4.0 10.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • myBB Group Forum Software

Classification

Weakness
  • CWE-912 Hidden Functionality
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.